DE 10 2006 027 487 A1 shows a vehicle tank for an aqueous urea solution in which there is an internal tank. A pump conveys the urea solution both out of the tank and also out of the internal tank of the tank to the exhaust gas line of an internal combustion engine. Ventilation takes place by way of a pressure control valve which is connected both to the internal tank and also to the outlet side of the pump. An activated charcoal filter can be assigned to the pressure control valve in order to reduce odor emission.
The disadvantage is that the vehicle tank filled with the urea solution is provided with its own ventilation device in the form of a pressure control valve with an optionally connected activated charcoal filter which entails additional weight in the motor vehicle and increased production costs.
DE 102 14 556 A1 shows a fuel and reducing agent filling system which has a tank for fuel and a tank for the reducing agent. Both tanks can be filled from the exterior with the pertinent liquids and have their own devices for ventilation, the ventilation of the reducing agent tank being made as a combination vent valve.
The disadvantage is that the vapors of the reducing agent can flow unobstructed out of the reducing agent tank through the combination vent valve to the exterior and thus lead to a not inconsiderable odor problem.
DE 103 37 572 A1 shows a storage tank for fuel and auxiliary substances of an internal combustion engine and/or devices assigned or connected downstream from it, which is made conical or pyramidal and has a removal opening on the bottom of the storage tank. In the storage tank there is furthermore a heating device for heating the medium. There is a ventilation opening on the tip of the storage tank.
The disadvantage is that the vapors of the medium located in the storage tank are released to the exterior through the ventilation opening; this constitutes a strong odor problem and in the case of fuel vapors also entails an explosion hazard.
The object of the following invention is therefore to make available ventilation for a reducing agent tank which can be integrated into a motor vehicle in a manner as economical as possible and with little added weight, and which does not result in any odor problem in the vicinity.